• Journal of The Korean Association For Science Education
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• v.35 no.4
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• pp.619-628
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• 2015

The purpose of this study is to find out the effects of the diagnostic and formative assessment on elementary science classes. For this purpose, we developed the diagnostic and formative assessment test and provided them to students before giving them the equivalent and learning achievement tests. The results are described as follows: First, for the science class that took the diagnostic assessment; the test provided help in improving the students' learning achievement. Second, for the science class that took the formative assessment; the test did not provide help in improving the students' learning achievement and in improving their openness to learning opportunity only to self-directed learning attitudes. Third, for the science class that were given both the diagnostic and formative assessment test; the tests provided help in improving the students' learning achievement. It also helped in improving their openness to learning opportunity, initiative for learning, and passion for learning except in problem-solving skills on self-directed learning attitude. Therefore, I recommend the utilization of the diagnostic and formative assessment tests be provided to students in order to improve learning achievement and self-directed learning attitudes in science classes.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.1
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• pp.3627-3641
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• 1975

The Government is trying to increase total food grain yield to meet national self sufficiency by means of increasing unit yield as well as extending crop land, and this year he set the target of 321,000 hectare of forest to clear for cropping. This study was carried to investigate the most efficient method of clearing hillock by bulldozer, and successful method to develope yielding potential of newly cleared land in short term. Since the conventional land clearing method is just earth leveling and root removing neglecting top soil treatment, the growth of crop was poor and farmer tends not to care the land. The top-soil-furrowing method is applied through out this study, that is advantageous especially for the land having shallow top soil and low fertility like Korean forest. In this study, various operating method were tried to find out most efficient method separately in connection with the land slope less than 25 percent and over, and several fertilizing methods to develop yielding potential. The results are as follows; 1) For the natural land slope utilization method, applicable to the land having less than 25 percent slope, reverse operating was more efficient than using forward gear of bulldozer. The operating time was 3 hour 32 minutes and 36 seconds using forward gear was 2 hour 32 minutes and 30 seconds for reverse gear operation per 1,000 square meter. 2) Bulldozer having angle blade adjustment needed 7hr 15min. for constructing of terrace per 10a compaire with the one having angle & tilt adjustment needed 6hr 4min for same operations. Specially there is significant difference for operation time of first period (earth cutting) such as bulldozer having angle blade adjustment needed 3hr 56min compaired with the one having angle & tilt adjustment 3hr 59min. In construction of terrace, the bull-dozer having tilting and angle blade adjustment was most suitable and performed efficiently. 3) For the fertilizer application treatment, the grass (Ladino clover) yield in first year was almost same as ordinary field's in the plot applied(N.P.K+lime+manure) while none fertilizer plot showed one tenth of it, and (N.P.K.+lime) applied plot yielded on third. 4) The effect of different land clearing method to yield showed significant difference between each treatment especially in the first year, and the conventional method was the lowest. In the second year, still conventional terracing plot yielded only half of ordinary field while the other plots showed as same as ordinary field's. 5) The downward top soil treatment plot showed most rapid improvement in soil structure during one year physio chemically, it showed increase in pH rate and organic composition, and the soil changed gradually from loam to sand-loam and the moisture content increased against the pF rate, and it gives good condition to grow hay due to the increase of field water capacity with higher available water content. 6) Since the soil of tested area was granite, the rate of soil errosion was increased about 2 to 5 percent influencing in soil structure more sand reducing clay content, and an optimum contour farming method should be prepared as a counter measure of errosion.

• 전자공학회논문지 IE
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• v.45 no.4
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• pp.11-18
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• 2008

This study is implementation of attitude control system(ACS - Attitude Control System). for a multi legs robot. This study designs H/W of Inertial Measurement Unit (IMU) and attitude control algorithm S/W. Compare performance with Mtx and MTx in order to verify action performance of this system after implementation, and will verify a system integrated IMU of a multi-legs robot. ACS uses Gyro and an accelerometer and an earth magnetism sensor, and it is a system controlling a roll, pitch angle attitude of an object. Generally, low price MEMS is difficult to calculate a correct situation of an object as an error occurs severely the Inertial sensor. This study implements IMU in order to develop ACS as use MEMS, accelerometer, Gyro sensor and earth magnetism sensor. Design algorithm each a roll, pitch, yaw attitude guaranteeing regular performance, and do poling in a system as include an attitude calculation program in an IMU system implemented. Mixed output of Gyro and an accelerometer, and recompensed a roll, pitch angle, and loaded in this study on a target platform in order to implement the ACS which guaranteed performance more than a continuously regular level, and operated by real time, and did porting, and verified.

• Journal of the Korean earth science society
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• v.27 no.3
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• pp.279-288
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• 2006

We incorporated cooperative learning focusing on the 'Crustal Deformation' in five classes of second grade students, at an all-girls' middle school of Gimje city. The groups of cooperative learning were composed of four members of students each, according to the heterogeneous level. We conducted a pretest on the students' preference before incorporating the cooperative learning. After ten weeks of cooperative school work, the students took a post test with the same questions as the pretest. The result of this method greatly impacted the change on the students' scientific preference. It means that the students showed a positive change in their awareness of and participation in science classes, compared to before. However it is difficult to distinguish the differences in their scientific attitude on the recognition about scientists and habits which make them think scientifically. This resulted from the short period of ten weeks which is not sufficient to carry out the study strategy effectively. Surveys of the students on cooperative learning indicates that the middle level students prefer this method unlike the higher or lower level students. we are convinced that they can learn from the students of higher level and are able to help the lower level with the interaction through cooperative learning. According to the result of the survey, the method has some weaknesses; it arouses the high noise levels and consequent disturbance due to verbal interaction and of conflicts due to disagreements when they discuss the process. On the contrary, advantages are developing the students's interest in science class, helping them to learn, creating positive participation in class, and fostering mutual collaboration with other students through cooperative learning.

• Korean Journal of Remote Sensing
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• v.34 no.6_2
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• pp.1273-1282
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• 2018

Recently, active research on the Arctic Ocean has been conducted due to the influence of global warming and new Arctic ship route. Although previous studies already calculated quantitative extent of sea ice using passive microwave radiometers, melting at the edge of sea ice and surface roughness were hardly considered due to low spatial resolution. Since Sentienl-1A/B data in Extended Wide (EW) mode are being distributed as free of charge and bulk data for Arctic sea can be generated during a short period, the entire Arctic sea ice data can be covered in high spatial resolution by mosaicking bulk data. However, Sentinel-1A/B data in EW mode, especially in HV polarization, needs significant radiometric correction for further classification. Thus, in this study, we developed algorithms that can correct thermal noise and scalloping effects, and confirmed that Arctic sea ice and open-water were well classified using the corrected dual-polarization SAR data.

• Journal of the Korean Society of Earth Science Education
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• v.11 no.3
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• pp.203-211
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• 2018

The purpose of this study is to investigate the effects of Project-Based Learning on Science Concepts and Science Learning Motivation. This particular study was proceeded to 4th grader at S elementary school, there was a mutual agreement with a homeroom teacher about assigning a research group and comparison group and it was agreed to students by explaining the reason and purpose of the study. There searcher visited in person to pick 22 students for research group and another 20 students for comparison group. For a research group, an experimental group, homeroom teacher, proceeded a science class with the application of Project-Based Learning. The experimental period was set up as a 40 minutes class unit for 12 weeks. After an experimental group, Science Concepts and Science Learning Motivation were examined, data collection and data analysis were proceeded by order. The following experimental results are as below. First, the application of Project-Based Learning method in a class was effective in improvement of Science Concepts acquisition. Second, the application of Project-Based Learning method in a class was effective in cultivation of Science Learning Motivation. Third, the application of Project-Based Learning method in a class had a positive cognition from the learners in the experimental group. Based on the discussions and implications of the results of this study, some suggestions in the follow - up study are as follows. First, applying Project-Base Learning to various science lessons and learning effects can be suggested as one of the new teaching methods. Second, the use of the Project-Based Learning to test the effects of elementary school students' different grades may be regarded as another teaching method for science class.

• Journal of the Korean Society of Earth Science Education
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• v.11 no.3
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• pp.172-181
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• 2018

The purpose of this study is to investigate the impact on self-directed learning ability and science process skills by utilizing 'Thinking Maps' in a science class. This particular study was proceeded to 5th grader at B elementary school, there was a mutual agreement with a teacher about assigning a research group and a comparison group and it was agreed by students and explaining the reason and purpose of the study. The researchers visited the school and selected 24 students in the research class and 24 students in the comparative class. For a research group, an experimental group, homeroom teacher, proceeded a science class with the application of 'Thinking Maps'. The experimental period was set up as a 40 minutes class unit for 12 weeks. After an experimental group, self-directed learning ability and science process skills were examined, data collection and data analysis were proceeded by order. The following experimental results are as below. First, the application of 'Thinking Maps' method in the class was effective in self-directed learning ability. Second, the application of 'Thinking Maps' method in the class was effective in scientific process skills. Third, the application of 'Thinking Maps' method in the class had a positive cognition from the learners in the experimental group. Based on the discussions and implications of the results of this study, some suggestions in the follow - up study are as follows. First, applying Thinking Maps technique to various science classes to see the effects can also be suggested as one of the new teaching methods. Second, testing the effects of applying different grades of elementary school students using the Thinking Maps technique could also be highlighted as another way of teaching science classes.

• The Journal of Engineering Geology
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• v.31 no.3
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• pp.381-393
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• 2021

Physical, mechanical, hydraulic, and geophysical tests were applied to validate methods of inspecting the effectiveness of grouting on an agricultural reservoir dam. Data obtained from series of in situ and laboratory tests considered four stages: before grouting; during grouting; immediately after grouting; and after aging the grouting for 28 days. The results of SPT and triaxial tests, including the unit weight, compressive strength, friction angle, cohesion, and N-value, indicated the extent of ground improvement with respect to grout injection. However, they sometimes contained errors caused by ground heterogeneity. Hydraulic conductivity obtained from in situ variable head permeability testing is most suitable for identifying the effectiveness of grouting because the impermeability of the ground increased immediately after grouting. Electric resistivity surveying is useful for finding a saturated zone and a seepage pathway, and multichannel analysis of surface waves (MASW) is suitable for analyzing the effectiveness of grouting, as elastic velocity increases distinctly after grouting injection. MASW also allows calculation from the P- and S- wave velocities of dynamic properties (e.g., dynamic elastic modulus and dynamic Poisson's ratio), which can be used in the seismic design of dam structures.

• Journal of the Korean Geosynthetics Society
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• v.20 no.4
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• pp.19-32
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• 2021

In this study, evaluation and consideration of domestic/overseas design, construction, and quality control performed by the authors on the deep cement mixing method were performed, and improvements for the development of the DCM method were suggested in the future. As a result of this study, it was found that the cross-sectional area correction for strength is required during the laboratory test of mix proportion, and caution is required because the extrapolation method may lead to different results from the actual one. Applicable design methods should be selected in consideration of both the improvement ratio and the type of improvement during design, and it was confirmed that the allowable compressive strength to which the safety factor was applied refers to the standard value for stability review and not the design parameters. In the case of the stress concentration ratio, rather than applying a conventional value, it was possible to perform economical design by calculating the experimental and theoretical stress concentration ratio reflecting the design conditions. In the case where pre-boring is expected during construction, if the increased water content is not large compared to the original, there were cases where a major problem did not occur even if the result that did not consider the increase in water content was used. In addition, it was confirmed that when the ratio of the top treatment length to the improved length is high, a small amount of design cement contents per unit length can be injected during construction. In the case of quality control, it was evaluated that D/4~2D/4 for single-axis and D/4 point for multi-axis were optimal for coring of grouting mixtures. As an item for quality control, it is judged that the standard that considers the TCR along with the unconfined compressive strength of grouting mixtures is more suitable for the domestic situation.

• Journal of the Korean Society of Earth Science Education
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• v.14 no.3
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• pp.257-266
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• 2021

This study investigated the understanding of pre-service teachers in relation to the 'fog experiment' in the 5th grade 'Weather and Our Daily Life' unit of the 2009 and 2015 revised elementary school science textbooks. Pre-service teachers who participated in this study were 100 students, who are attending the university of education and taking courses in teaching research. After pre-learning about the 2009 and 2015 revised elementary school science textbooks and guide book, pre-service teachers conducted the experiment in groups. After that, the pre-service teachers individually presented answers to three questions, and the results of analyzing the answers are as follows. First, there were 24 (24%) preservice teachers who explained the difference in fog generation in the 2009 and 2015 revised curriculum with related scientific concepts such as condensation and water vapor, and only 1 (1%) of them explained the difference using the concept of saturation. Second, there were 48 (48%) pre-service teachers who found out the reason for the change in the fog experiment method according to the change in the curriculum. Third, pre-service teachers valued the reproduction and success of experiments rather than the importance of scientific knowledge, and such pre-service teachers suggested the use of alternative experiments or website.